A TV receiver or a computer monitor often employs a liquid crystal display (LCD) or a plasma display panel (PDP) to replace a cathode ray tube (CRT). Recently, the rapid advancement of the semiconductor techniques makes LCD panels, particularly color LCD panels more popular and less expensive.
An LCD panel is a passive display device in that the LCD panel displays light information signal that has been light-converted but does not itself emit light. Thus, an LCD device needs a light source such as a backlight unit. A conventional LCD device commonly uses a backlight unit employing a plurality of lamps to emit enough light to illuminate the LCD panel. However, a plurality of lamps not only consume a large amount of energy, but also limit the size, weight, and operational environment of the LCD device.
Some LCD devices use external light to improve the backlight unit. For example, published US patent application no. 2010/0073791 to Mahowald (the '791 application) discloses an apparatus for harnessing external light to illuminate a display screen of an electronic device. However, the '791 application explicitly addresses the problem where the external or ambient light is brighter than the illumination of the display screen by collecting external light to help illuminate the display screen. Therefore, the '791 application may not be able to overcome the shortcomings of the conventional LCD devices.
Therefore, it would be beneficial to provide systems and methods employing natural light or external light as the light source to illuminate an LCD panel. The disclosed methods and systems are directed to solve one or more problems set forth above and other problems.